Conventional gasoline fueled four-stroke engine used in hand-held applications as in a trimmer and a blower sold by Ryobi and MTD and gaseous fueled blower by LEHR are environmentally friendly. However, the drawback is that those engines are very heavy and cannot be operated upside down for extended time and the same design cannot be used in chainsaws. Alternative two-stroke engines are advantageous, but very high in emission levels. Gaseous fueled two-stroke trimmer engine as manufactured and sold by Mitsubishi is a conventional two-stroke engine, which has significantly higher pollutants in the exhaust. Some conventional two-stroke engines sold in US have catalysts to lower the emission levels.
It is known in the engine industry that there are gaseous fueled two-stroke engines with oil injection system. However, these engines are conventional type which have high emission levels and the cleaner stratified engines are gasoline fueled and typically have oil pre-mixed with the gasoline. The disadvantage with gasoline fuel is that they smell bad when spilled and evaporate when stored for longer time. Secondly users have to always pre-mix oil for lubrication, which can harm the catalysts and as such emission levels may be bad toward the end of the life of the catalyst and or the engine. Thirdly, user may forget to mix oil with the gasoline which results in a scuffed engine.
The design described here has a gaseous fueled stratified two-stroke engine with a dual passage carburetor to lower the emissions and oil injection to lubricate the engine. The engine may further be fitted with catalysts to reduce the pollutants to even way below the legal limits. The gaseous fuel may be Butane, CNG, Methane, Hydrogen, or Propane or mixture of any gaseous fuels in any ratio. The engine can be used in many hand-held and lawn garden and mobile applications such as chainsaws, trimmers and scooters.